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Oracle
Oracle is one of the most popular relation database management systems (RDBMS) in the technology market today. A database is a collection of data organized into rows known as tuples and columns known as attributes. Each data entry is known as a data record in the database. A database table is a collection of tuples. A relational database management system uses the relational model to store data. Being one of the largest database management systems, it also offers one of the largest feature sets as well. Unlike many smaller SQL databases, Oracle has a large team of technical writers that work on documentation, tutorials, and upkeep to make sure that you have all the support you need when using Oracle. In fact, all of the documentation for newer versions includes a list of changes to make learning new versions even easier. However, this comes at a cost; Oracle is also one of the most expensive database solutions today, costing companies tens of thousands of dollars. On the bright side, Oracle began offering a free solution beginning with their version 10g software known as Oracle Express Edition which is free to use but has many limitations to prevent larger companies from using it. According to GeekInterview.com, Oracle excels due to it’s strict adherence to the ACID test which is as follows: Atomicity: That is Results of a transaction's execution are either all committed or all rolled back. Consistency: The database is transformed from one valid state to another valid state. Illegal transactions aren't allowed and, if an integrity constraint can't be satisfied then the transaction is rolled back. Isolation: The results of a transaction are invisible to other transactions until the transaction is complete thus increasing the security on data. Durability: Once committed (completed), the results of a transaction are permanent and survive future system and media failures and thus ensuring maintenance and protection of data. All the above are well maintained by Oracle database. The Oracle company was created by Lawrence J. Ellison 1977 and it was first relational database software to support structured query language, more commonly known as SQL. The California based company is often used on websites and for e-commerce businesses. Oracle is often used for large commercial databases. With Oracle you can link various database tables together to create relationships between the tables through keys. Oracle allows you to insert, query, alter and delete information in databases. Some common keywords that Oracle uses with SQL are Select, Where, From, Group by and Order by. With the “Select” keyword you can select the attributes in the table that you would like to view. The “Where” keyword allows you to sort through the tuples in the table you have chosen. The “From” keyword enables you to select which table you would like to look at. The “Group” by keyword uses aggregate functions such as sum() and avg() to calculate. Lastly, the “Order by” keyword orders the data you have selected in to the way you wish it to be ordered by. These keywords are used to query tables with SQL.